With an eye on the environment and another your own health, it’s never been a better time to start eating less meat and more vegetables. Cutting down on animal protein does more than slash calories—it lowers your cholesterol and blood pressure, as well as your risks of heart diseases, diabetes and cancer. And eating less puts less of a strain on the environment. Where to start with switching your diet can seem like a daunting task, so here’s a plan that will help you accomplish this gradually over the course of three weeks.